support templating language when constructing API calls

[newgene]

Translating from the SmartAPI's x-bte annotations (passed as bteEdges), call-apis constructs the actual API calls (like GET or POST queries) in builder_factory.

The current algorithm does not support multiple input values, only input[0] is accepted. And we should also support a set of predefined filter functions for common parameter transformation (e.g. concatenation, substr, trimming , add/remove CURIE prefixes etc).

We can use a common templating language to enhance the flexibility and capacity of the builder_factory, e. g. the commonly used mustache templating language can be a good option.

A nice mustache reference: http://cocoadocs.org/docsets/GRMustache.swift/0.9.3/

[newgene]

relevant to this issue: biothings/biothings_explorer#147

[colleenXu]

This is an issue I would like updates on. Since I would want to update the x-bte annotations if we have a more sophisticated way of specifying the query structure.

One goal from my perspective is:

• some APIs expect their inputs to have prefixes. So I would like to be able to specify "append this prefix to each input ID, and then send the whole set of IDs to the API as a batch query" for APIs that can support batch-querying.

[colleenXu]

Closing this issue for now, since it seems to be addressed by the PRs. Will reopen this issue or open new issues if this needs additional work